Modern household showers are provided with one or more standard pipe shower arms connected to the household water plumbing system. A showerhead is typically attached to the shower arm by screw threads provided on the showerhead and mating screw threads provided on a free end of the shower arm. The mating screw threads allow the showerhead to be connected to the shower arm by engaging the mating threads and rotating the showerhead relative to the shower arm. Typical showerheads are configured with a balljoint that allows the showerhead to swivel around the axis of the shower arm, such that the showerhead will remain oriented for proper operation, even after the ball joint has been rotated any suitable amount to attain a sufficiently tight connection to the shower arm. Other accessories also designed to be fitted to shower arms have swivels to allow the accessory to be positioned for proper operation regardless of the angular position of the threads required to achieve a liquid tight seal with shower arm.
Various types of hair shampoo, hair conditioner, soap, skin conditioner, moisturizer, perfume and other personal care products are available for use in showers. Typically, such products are distributed in plastic bottles or other containers that are kept within the shower stall. The bottles and other containers tend to collect inside of the shower stall, resulting in possible safety and health problems, as well as causing the shower to appear cluttered.
Dispensing units have been designed for installation in a shower stall, for dispensing quantities of flowable shampoos, conditioners, soaps into a user's hand. Other dispensing units that were configured to be connected in the water flow system have not gained significant popularity. It is believed that one reason for the lack of popularity of such previous dispensing systems is the difficulty of refilling such systems and of connecting such systems without changing the orientation or operation of the showerhead or dispensing system. Another reason is that regulatory restrictions placed on the maximum flow rate of water through a showerhead has introduced flow controllers into the showerheads that raise the water pressure in the shower arm to a level where it is difficult for a conventional venturi system to work effectively. An example of a previous dispensing unit using a venturi system is described in U.S. Pat. No. 3,231,200, the contents of which are incorporated herein by reference.